Electric heating pad



Jxme 30, 1942. E. A. DmscoLL ELECTRIC HEATING PAD Filed June 9, 1941Edward A. Huscoll,

INV ENTOR.

Patented June 30, 1 942 UNITED STATES PATENT OFFICE ELECTIITIC HEATINGPAD Edward A. Driscoll, Jamaica, N. Y.

Application June 9, 1941, Serial No. 397,166

8 Claims.

The invention here disclosed relates to heating pads, such as employedfor diathermic purposes.

Objects of the invention are to provide a pad of this general type,which will provide the desirable characteristics of a moist, as distinctfrom a dry heat, which will be variously controllable to suit therequirements or comfort of a patient and which will Abe entirely safeand practical in every way.

Other desirable objects and the novel features by which the purposes ofthe invention are attained will appear in the course of the followingspecification.

The drawing accompanying and forming part of the specificationillustrates one of the present commercial embodiments of the invention.Structure however may be modified and changed as regards the presentdisclosure, all within the true intent and broad scope of the inventionas hereinafter dened and claimed.

Fig. 1 is a broken and part sectional View showing one of the pads andthe manner in which it may be connected for use, the pad being shown inthe open, inoperative condition.

Fig. 2 is an enlarged cross-sectional view of the pad in the closedoperative condition, taken as on the line 2-2 of Fig. 1.

Fig. 3 is a broken and further enlarged crosssectional detail as on line3 3 of Fig. 1.

Fig. 4 is a broken sectional detail of a modied form of the invention.

In the present invention, the principle covered by the Driscoll Patent1,943,062, Jan. 9, 1934, is utilized by incorporating relativelyinsulated conductors of opposite polarity in a pad formation which canbe moistened as required to afford a desired degree of heat producingconductivity between the conductors.

In Fig. l, the opposite conductors are shown in the form of two spacedgrids, one composed of a bus bar 5, and branches 6, and the other a busbar 'I, and branches 8, and arranged with the branches in spacedalternating order, held so by a surrounding and enclosing pad 9, ofabsorbent normal insulating material, such as asbestos.

This absorbent pad with embedded conductors is shown as located andremovably retained in position over approximately one-half of a foldablebase pad I0, of suitable insulating absorbent material, such as spongerubber.

The means for so locating and retaining the absorbent grid pad on thefoldable base pad is shown as an overstanding strap II, of elasticmaterial beneath which the grid pad may be slipped.

The two pads are shown as mounted in a foldable case I2, composed offlexible, water-proof and insulating material, such as rubber orrubberized fabric and having a continuous edge flange I3, carryingcooperable fasteners Il, engageable and disengageable by the slider I5.

The electrical connections may vary, but a preferred arrangement isshown in Fig. l, in which the wires I6, I1, are led separately throughopen'- ings I8, I9, in the back of the folder to terminals 20, 2|, onthe back of the folding pad, said wire terminals being connected with orforming part of contacts 22, 23, engageable respectively with companiongrid terminals 2l, 25.

The companion engaging contacts 22, 2|, and 23,125, may be of the springengaging glove fastener type, so as to insure good contact and at thesame time serve as fasteners for securing the folding pad closed overthe grid pad as in Fig. 2.

This construction operates as a safety switch, insuring that the basepad be folded closed over the grid pad. before the circuit is closed tothe opposed, cooperable heater grids.

The foldable base pad may be adhesively or otherwise attached at theback to the folding case, so that the latter may be opened and closedlike a book, to open or to close the heating circuit to the grids.

By using til: slide fastener, the folder may be entirely closed, toprevent accidental opening of the circuit at the snap fastener contacts.This closing of the folder about the edges of the pads also serves toretain the heat generated by the flow of current through the moistenedabsorbent medium between the grids.

The rate of heating and total heat may be governed by the extent towhich the insulatingwhen-dry medium separating the opposed grids ismoistened. With more wetting, the heating will be faster and sensibleheat generated will be greater than when the absorbent material iswetted, for instance, 'only enough to make it conductive.

The moisture usually may be applied directly to the absorbent grid pad,when the folder is in the open condition, shown in Fig. 1, and thereforebefore there are any electrical connections to that pad.

A s a further safety precaution, some form of current limiting means arepreferably interposed in the supply circuit leading to the pad.

In the example illustrated, a table supported base 26, is interposed inthe supply cord circuit 21, said base carrying two lamp sockets 28, 29,one in each side of the line to take lamps 30, 3|, fuses or the like.

This double socket form of construction is particularly desirable inenabling the use of different combinations, such as for instance. acurrent limiting lamp in one side of the line and a protective fuse orthe like, in the other side of the line.

'Ihe grid pads are readily removable and replaceable, thus enablingquick substitution of a fresh pad or a pad of different absorptive orelectrical characteristics. Grids of different forms will providedifferent heating characteristics. Thus heating units of differentoperating characteristics can be readily substituted and used in thesame holder or folder. The individual may control the heating effects bym'oistening the absorbent grid pad to different extents and by the useof different size lamps and in one or both sides of the line, and thelike.

The asbestos or other insulating-when-dry absorbent medium may be in afibrous, matted, felted,` twisted or Woven state and may be wrapped,molded, or otherwise placed about and secured over the companion grids.

The grids may be stamped out of thin flat sheet metal, so that the padwhen made up will be sufficiently light and flexible.

If desired, the grids may be of tubular form and moisture be suppliedtherein, said grids then having suitable openings for escape of themoisture into the surrounding material of the absorbent pad. Themoisture may be supplied by liquid or connections may be made to supplysteam into such hollow grids.

In Fig. 4, lgrids of tubular form are illustrated at 32, 33, havingsuitable liquid or moisture supply connections thereto at 34, 35.

The lamp form of current control illustrated may be desirable, becauseof the visual indication thereby provided of the amount of current, orthe presence or absence of any current in the pad, but it iscontemplated that any other form of control may be employed, such forexample, as the adjustable resistance switches employed in connectionwith ordinary heating pads.

What is claimed is:

l. An electric heating pad, comprising a flexible pad of absorbentmaterial, flexible conductors of opposite polarity confined in opposedspaced relation by the absorbent material of said pad and which materialis electrically insulativewhen-dry and conductive when wet, a flexibleenclosure about said pad and including a folder and circuit completingmeans for said pad carried by said folder and cooperable to carrycurrent to said conductors only when the folder is closed.

2. An Velectric heating pad, comprising a flexible pad of absorbentmaterial, flexible conductors of opposite polarity confined in opposedspaced relation by the absorbent material of said pad and which materialis electrically insulativewhendry and conductive when wet, a flexibleenclosure about said pad and 'including a folder and a flexible foldablebase pad in said folder .and supporting said absorbent pad, said folderhaving a flange about the edge of the same for positioning and retainingsaid foldable base pad in either the open or the folded condition ofsaid folder and base pad and means for securing said flange closedtogether about the base pad when the folder and the base pady are in theclosed folded condition.

3. An electric heating pad, comprising a flexible pad of absorbentmaterial, flexible conductors of opposite polarity confined in opposedspaced relation by the absorbent material of said pad and which materialis electrically insulativewhen-dry and conductive When wet, a flexibleenclosure about said pad and including a folder, a flexible foldablebase pad in said folder and supporting said absorbent pad, terminalmeans on said absorbent pad for the conductors enclosed therein andcooperable terminal means on said foldable pad, said cooperable terminalmeans being positioned on said foldablepad to engage and carry currentto the terminal means on said absorbent pad only when said foldable padis folded about said absorbent pad.,

4. An electric -heating pad, comprising a flexible pad of absorbentmaterial, flexible conductors of opposite polarity conflned'in opposedspaced relation by the absorbent material of said pad and which materialis electrically insulative-When-dry and conductive when Wet, a flexibleenclosure about said pad and including a folder, electrical terminals onsaid folder and companion terminals on the absorbent pad engageable bysaid first terminals only when the folder is closed.

5. An electric heating pad, comprising a flexible pad of absorbentmaterial, flexible conductors of opposite polarity confined in opposedspaced relation by the absorbent material of said pad and which materialis electrically insulativewhen-dry and conductive when Wet,A a flexibleenclosure about said pad, including'a folder and a foldable base pad ofsponge rubber in said folder and supporting and foldable about saidabsorbent pad.

6. An electric heating pad, comprising a flexible pad of absorbentmaterial, flexible conductors of opposite polarity confined in opposedspaced relation by the absorbent material of said pad and which materialis electrically insulativewhen-dry and conductive when wet, a flexibleenclosure about said pad and including a folder, electric terminals onthe inside of said folder, wires extending through the back of saidfolder to said terminals and companion terminals on the absorbent padengageable by said first mentioned terminals when the folder is closed.

7. yAn electric heating pad, comprising a flexible pad of absorbentmaterial, flexible conv ductors of opposite polarity confined in opposedspaced relation by the absorbentmaterial of said pad and which materialis electrically insulativewhen-dry and conductive when wet, a flexibleenclosure about said pad and including a folder, electric terminals onthe inside of said folder, wires extending through the back of saidfolder to said terminals, companion terminals on the absorbent padengageable by said rst mentioned terminals when the folder is closed andelectrical connections to said conductors, including circuit wires and adouble socket base interposed in said circuit wires and connected withone socket in one side of the line and the other socket in the otherside of the line.

moisture furnishing medium to said absorbent material, through the meansof said tubular conductors and thereby to control conductivity betweenthe conductors while said electric heating pad is in service.

EDWARD A. DRISCOLL.

